There conventionally is a thermoelectric generating device which converts thermal energy to electric energy by a thermoelectric generating element using the Seebeck effect. It becomes possible to recover a large amount of waste heat heretofore exhausted in factories, power plants, incinerators and the like as the electric energy by using the thermoelectric generating device. There is the thermoelectric generating device which outputs at a maximum power point or an optimal operating point based on voltage current characteristics of the thermoelectric generating element as disclosed in Patent Literatures 1 to 3, for example.